Here's a how-to that I thought folks might be interested in. I can't take credit for the idea of the "build your own" bipod lock, I saw the idea here somewhere in a post which I can no longer find.
The build-your-own lock consists of only 2 parts, and takes less than 15 minutes to install. You will need to order one each of the following from McMaster-Carr
64835K32 Die Cast Zinc Teardrop Adjustable Handle 10-32 Threaded Insert, .32" Thread Depth, Black $5.00/ea
93013A220 Black-Finish Aluminum Unthreaded Round Spacer 3/8" OD, 1/4" Length, #10 Screw Size, .192" ID $1.05/ea
Note that when I ordered these parts, shipping was an outrageous $10+ on the order. If you can find some buddies to go in with you, you can amortize the shipping cost over several sets, which could get the price down to about $7-$8 per set.
The only tool you will need to install this bipod lock is a 1/4-inch scoket to remove the retaining nut for the original thumbscrew.
Before you start, the original Harris bipod thumbnut assembly will look like this:
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Remove the hex nut in the center of thumbnut, then unscrew the thumbnut and remove it. Note that on the other end of the screw the thumbnut was on is a cross drilled hole with a pin through it. When you remove the thumbnut, that pin can fall out. Be careful not to lose it.
Once you have removed the thumbnut, the bipod should look like this:
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Now, take the spacer and slip it over the exposed screw. The spacer keeps the locking lever away from the bipod body, and also makes the exposed thread length correct for the threaded hole in the locking lever:
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Now simply screw the locking lever onto the exposed part of the locking screw. DO NOT use an allen wrench to turn the socket head fastener in the middle of the lever. This fastener just retains the ratchet of the lever, and you will break it if you over torque it (I speak from experience ). You might have to fiddle with the pin I warned you about above, in order to make sure it is seated correctly in the slots it fits in. Once you are done, the bipod should look like this:
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That's all there is to it!
Finally, the cool thing about these levers is that they are spring loaded with a ratchet type mechanism (althtough they do not ratchet like a ratchet you would use on a socket). To adjust the position of the locking lever, simply pull it toward you to disengage it, rotate it to where you want it, then let it go. You should be able to find a position where you can just move the lever a small bit to unlock the bipod, but will leave the lever out of the way in the locked position.